Fig. 7.

LC-ESI–MS/MS spectrum of the linear surfactin precursors. a Linear surfactin precursors ion [M + H]⁺ at m/z 1026 at retention time 5.26 min containing a Glu1-Leu/Ile2-Leu3-Val4-Asp5-Leu6-Leu/Ile7 peptide and a C13 β-hydroxy fatty acid chain. b Linear surfactin precursor ions [M + H]⁺ at m/z 1026 at retention time 5.53 min containing a Glu1-Leu/Ile2-Leu3-Val4-Asp5-Leu6-Val7 peptide and a C14 β-hydroxy fatty acid chain